Round disc with non-circular back-up pad



p 1952 D. R. LOWTHER ETAL 3,054,232

ROUND DISC WITH NON-CIRCULAR BACK-UP PAD Filed Sept. 20, 1960 INVENTORS DWIGHT R. LOWTH ER By HOWARD R.WRIGHT ATTORNEY United States Patent 3,054,232 ROUND DISC WITH NON-CIRCULAR BACK-UP PAD Dwight R. Lowther, Waterford, and Howard R. Wright, Troy, N.Y., assignors to Norton Company, Troy, N.Y.,

a corporation of Massachusetts Filed Sept. 20, 1960, Ser. No. 57,226 2 Claims. (Cl. 51-195) The present invention relates in general to an improved abrasive cutting tool and more specificaly to a method and means for improving the cutting efliciency of a coated abrasive disc.

Heretof-ore the coated abrasive disc, which may be defined as a disc, the backing of which comprises paper or other non-woven cellulose material and/ or cloth, which disc is provided with a coating of abrasive grains and is relatively stiff and rigid in its own plane and has the capacity of resisting torsional and buckling strains and of flexing under lateral pressure and which is constructed to be held from the center and used with yieldingly supported pads, has been developed as an extremely important industrial and household tool. Generally such discs have been used with back-up pads formed from rubber or the like wherein the back-up pads conformed in general to the shape of the disc. In other words, where a circular disc was used, the back-up pad was also circular in shape although it might have a somewhat shorter radius than the radius of the disc and where the disc was other than circular, e.g. hexagonal, the pad also was hexagonal.

A recent development which is described and claimed in the copending application of Leland H. Vorce, Serial No. 9,345, filed February 17, 1960, and now abandoned, is that of an abrasive disc having a configuration equivalent to that of a circular disc from which has been out two parallel chords-equi-spaced from the center of the disc, giving a structure with a pair of arcuate cutting edges connected by two straight edges. This disc which has substanital use in certain industrial applications is mounted for use on a similarly shaped back-up pad as has been conventional practice.

It has now been found that the cutting efiiciency of the ordinary round or polygonal disc can be greatly improved by mounting such disc on the back-up pad described in connection with the abrasive disc of the aforesaid Vorce application.

Accordingly, it is an object of the present invention to provide an improved coated abrasive tool.

It is a further object of the invention to provide a method and means for increasing the cutting efiiciency of conventional coated abrasive discs.

Additional objects, if not specifically set forth herein, will be readily apparent to one skilled in the art from the following detailed description of the invention:

In the drawings:

FIGURE 1 is a perspective view of a coated abrasive disc mounted in accordance with the present invention and partially cut-away to show the back-up pad.

Generally, the present invention comprises mounting an abrasive disc for rotation on a back-up pad of a configuration other than that of the abrasive disc.

More specifically, the present invention includes the positioning of a conventional circular abrasive disc on a 3,054,232 Patented Sept. 18, 1962 power-driven back-up pad having one major planar axis longer than the other and having an arcuate edge at each end of said major planar axis.

Referring now to the drawing, the abrasive disc 10 consists of the paper and/or cloth backing member 11 with a coating of abrasive grains 12 bonded thereto by a resin or glue adhesive. The representation of the disc 10 has been cut-away as at 13 to show the back-up pad 14 formed of hard rubber or the like. The abrasive disc 10 is secured .to the pad 14 by any suitable holding means as illustrated at 15. Pad 14 is formed with arcuate edges 16 and 16 conforming generally to that portion of the periphery of abrasive disc 10 immediately adjacent thereto, and a pair of straight connecting sides 17 and 17. The portions of the pad covered by the disc have been shown in dotted lines to permit better visualization or the combination.

In operation, it has been found that this combination of disc and backup pad produces surprising results in the amount of abrading that can be done with any given abrasive disc. The intermittent support afforded by the pad of difierent configuration than the disc permits a beating action of the disc against the workpiece, resulting in greatly improved cut. A limited and controlled degree of automatic slippage between the disc and the back-up pad is desirable in order to insure that the entire surface of the disc is used in the abrading process.

The following examples are illustrative only and are not intended as limitations upon the scope of the present invention other than as may appear from the appended claims.

EXAMPLE 1 A test Was run with two identical circular vulcanized fiber coated abrasive discsgrit 36--one mounted on a conventional back-up pad (circular) and the other mounted on a pad such as described in the aforesaid Vorce application. The two discs were tested on the same power-driven spindle under a dead weight of 9 pounds and at an angle of 10 to the workpiecein each instance a 4" x 1 /8 x 13" piece of No. 1020 hot rolled steel plate. Readings were taken at 1 or 2 minute intervals and the test continued until the rate of cut (or stock removal) reduced below 5 grams in any 2-minute period.

Table A below is the conventional disc plus the conventional circular back-up pad. The total cut for this disc was arbitrarily designated as Table B below is the conventional disc plus the noncircular pad described above.

3 'Table B Total percent out Time interval (m1n.)

Cut i Shed (qms.)

Conventional disc plus non-circular pad.

H t- H iolomcamo mcemoco oHcoHrozoooooHHHHrwww- O ODOQQOOOCQOOODQOOQO N pppppppppppps p pp Total At this point the pad was indexed approximately 90.

The test showed an improvement in cut of better than times over the conventional disc and pad.

EXAMPLE 2 A second set of identical discs were tested under the same conditions as in Example 1 with the following results:

4 Table D Total percent piece, F. cut

Gut (q Shed (q Time interval (min) Conventional disc plus non-circular pad.

W c OQOOOOOOOOOOCQQODOOO a ppp ppp pswcppppppp Total Again the improvement in cut of the disc was marked when backed up by the pad having a diilerent configuration than that of the disc--in this case better than 6 times the total cut of the conventional combination.

It should be noted that in Examples I and II above, sufiicient slippage between the disc and the non-circular pad was allowed to permit the pad during the abrading operation to have an accumulative slip of about relative to its position as the start of the test.

Obviously many modifications and variations may take place without departing from the spirit and scope of the invention described herein and therefore only such limitations should be imposed as are contained in the appended claims.

We claim:

1. An improved abrading tool which comprises: a circular coated abrasive disc and a mounting pad therefor, said mounting pad having a major planar axis sub stantially equal in length to the diameter of said disc and a minor planar axis at right angles to and shorter than said major planar axis, said disc being aifixed to said pad so as to be rotated therewith against a workpiece.

2. A tool as in claim 1 wherein said pad has an arcuate edge at each end of said major planar axis.

Kent et a1 July 10, 1934 Tocci Dec. 14, 1954 

